Pose Tracking through Analysis of an Image Pyramid

Abstract

Techniques for tracking a pose of a textured target in an augmented reality environment are described herein. The techniques may include processing an initial image representing the textured target to generate feature relation information describing associations between features on different image layers of the initial image. The feature relation information may be used to locate features in different image layers of a subsequent image. Upon locating features in a highest resolution image of the subsequent image, the pose of the textured target may be determined for the subsequent image.

What is claimed is: 
     
         1 . A method comprising:
 under control of a computing device configured with computer-executable instructions,   capturing, with a camera of the computing device, a first image that at least partly represents a textured target in an environment in which the computing device is located;   generating a plurality of image layers for the first image, the plurality of image layers of the first image representing the first image at different resolutions;   detecting one or more features in each image layer of the plurality of image layers of the first image;   identifying a vector from a feature in a first image layer of the plurality of image layers of the first image to a feature in a second image layer of the plurality of image layers of the first image;   capturing a second image with the camera of the computing device;   generating a plurality of image layers for the second image, the plurality of image layers of the second image representing the second image at different resolutions;   based at least in part on the vector, searching a particular area in an image layer of the plurality of image layers of the second image to identify a feature that corresponds to the feature in the second image layer of the plurality of image layers of the first image; and   determining a pose of the textured target based at least in part on the identified feature in the image layer of the plurality of image layers of the second image.   
     
     
         2 . The method of  claim 1 , further comprising:
 utilizing the pose of the textured target to display augmented reality content on a display of the computing device in relation to a displayed location of the textured target.   
     
     
         3 . The method of  claim 1 , wherein the first image layer of the plurality of image layers of the first image has a lower resolution than the second image layer of the plurality of image layers of the first image. 
     
     
         4 . The method of  claim 1 , wherein searching the particular area in the image layer of the plurality of image layers of the second image comprises:
 aligning the vector to a location in a second image layer of the plurality of image layers of the second image that corresponds to a location of a feature in a first image layer of the plurality of image layers of the second image;   defining a search area in the second image layer of the plurality of image layers of the second image based at least in part on the aligned vector; and   searching within the search area to identify a feature in the second image layer of the plurality of image layers of the second image that corresponds to the feature in the second image layer of the plurality of image layers of the first image.   
     
     
         5 . The method of  claim 1 , further comprising:
 before capturing the second image, capturing a third image with the camera of the computing device;   generating a plurality of image layers for the third image, the plurality of image layers of the third image representing the third image at different resolutions;   based at least in part on the vector, identifying a feature in an image layer of the plurality of image layers of the third image that corresponds to the feature in the second image layer of the plurality of image layers of the first image; and   transforming the vector based at least in part on one or more characteristics of the feature in the image layer of the plurality of image layers of the third image,   wherein the feature in the image layer of the plurality of image layers of the second image is identified based at least in part on the transformed vector.   
     
     
         6 . The method of  claim 5 , wherein the one or more characteristics of the feature in the image layer of the plurality of image layers of the third image comprise:
 an orientation of the feature in the image layer of the plurality of image layers of the third image with respect to the feature in the second image layer of the plurality of image layers of the first image; and/or   a scale of the feature in the image layer of the plurality of image layers of the third image with respect to the feature in the second image layer of the plurality of image layers of the first image.   
     
     
         7 . A method comprising:
 under control of a computing device configured with computer-executable instructions,   obtaining first and second images that at least partly represent a textured target;   representing the first image with a plurality of image layers of different resolutions, the plurality of image layers of the first image comprising at least a first image layer and a second image layer;   generating feature relation information indicating a location of a feature in the second image layer of the plurality of image layers of the first image in relation to a location of a feature in the first image layer of the plurality of image layers of the first image;   representing the second image with a plurality of image layers of different resolutions;   based at least in part on the feature relation information, identifying a feature in an image layer of the plurality of image layers of the second image that corresponds to the feature in the second image layer of the plurality of image layers of the first image; and   determining a pose of the textured target based at least in part on the identified feature in the image layer of the plurality of image layers of the second image.   
     
     
         8 . The method of  claim 7 , further comprising:
 utilizing the pose of the textured target to display augmented reality content in relation to the textured target, the augmented reality content being displayed simultaneously with a substantially real-time image.   
     
     
         9 . The method of  claim 7 , wherein the feature relation information describes a vector from the feature in the first image layer of the plurality of image layers of the first image to the feature in the second image layer of the plurality of image layers of the first image. 
     
     
         10 . The method of  claim 9 , wherein identifying the feature in the image layer of the plurality of image layers of the second image comprises:
 aligning the vector to a location in a second image layer of the plurality of image layers of the second image that corresponds to a location of a feature in a first image layer of the plurality of image layers of the second image;   defining a search area in the second image layer of the plurality of image layers of the second image based at least in part on the aligned vector; and   searching within the search area to identify a feature in the second image layer of the plurality of image layers of the second image that corresponds to the feature in the second image layer of the plurality of image layers of the first image.   
     
     
         11 . The method of  claim 9 , further comprising:
 obtaining a third image, the third image being captured before the second image;   detecting a feature in an image layer of a plurality of image layers of the third image that corresponds to the feature in the second image layer of the plurality of image layers of the first image; and   transforming the vector based at least in part on the feature in the image layer of the plurality of image layers of the third image,   wherein the feature in the image layer of the plurality of image layers of the second image is identified based at least in part on the transformed vector.   
     
     
         12 . The method of  claim 11 , wherein the transforming the vector comprises changing a scale and/or orientation of the vector based at least in part on a scale and/or orientation of the feature in the image layer of the plurality of image layers of the third image. 
     
     
         13 . The method of  claim 7 , wherein determining the pose of the textured target comprises utilizing the identified feature in the image layer of the plurality of image layers of the second image and one or more other features in the image layer of the plurality of image layers of the second image to solve the Perspective-n-Point problem. 
     
     
         14 . One or more computer-readable storage media storing computer-readable instructions that, when executed, instruct one or more processors to perform the method of  claim 7 . 
     
     
         15 . A system comprising:
 one or more processors; and   memory, communicatively coupled to the one or more processors, storing executable instructions that, when executed by the one or more processors, cause the one or more processors to perform acts comprising:
 obtaining first and second images that at least partly represent a textured target; 
 representing the first image with a plurality of image layers of different resolutions, the plurality of image layers of the first image comprising at least a first image layer and a second image layer; 
 detecting one or more features in each image layer of the plurality of image layers of the first image; 
 generating feature relation information indicating a location of a feature in the second image layer of the plurality of image layers of the first image in relation to a location of a feature in the first image layer of the plurality of image layers of the first image; 
 representing the second image with a plurality of image layers of different resolutions; 
 based at least in part on the feature relation information, identifying a feature in an image layer of the plurality of image layers of the second image that corresponds to the feature in the second image layer of the plurality of image layers of the first image; and 
 determining a pose of the textured target based at least in part on the detected feature in the image layer of the plurality of image layers of the second image. 
   
     
     
         16 . The system of  claim 15 , wherein the feature relation information describes a vector from the feature in the first image layer of the plurality of image layers of the first image to the feature in the second image layer of the plurality of image layers of the first image. 
     
     
         17 . The system of  claim 16 , wherein identifying the feature in the image layer of the plurality of image layers of the second image comprises:
 aligning the vector to a location in a second image layer of the plurality of image layers of the second image that corresponds to a location of a feature in a first image layer of the plurality of image layers of the second image;   defining a search area in the second image layer of the plurality of image layers of the second image based at least in part on the aligned vector; and   searching within the search area to identify a feature in the second image layer of the plurality of image layers of the second image that corresponds to the feature in the second layer of the plurality of image layers of the first image.   
     
     
         18 . The system of  claim 16 , wherein the acts further comprise:
 before identifying the feature in the image layer of the plurality of image layers of the second image, transforming the vector by changing a scale and/or orientation of the vector.   
     
     
         19 . The system of  claim 15 , wherein determining the pose of the textured target comprises utilizing the identified feature in the image layer of the plurality of image layers of the second image and one or more other features in the image layer of the plurality of image layers of the second image to solve the Perspective-n-Point problem. 
     
     
         20 . The system of  claim 15 , wherein:
 the image layer of the plurality of image layers of the second image comprises an image layer from among the plurality of image layers that has a highest resolution; and   determining the pose of the textured target comprises determining the pose of the textured target with respect to the image layer of the plurality of image layers of the second image while refraining from determining the pose of the textured target with respect to other image layers of the plurality of image layers of the second image.   
     
     
         21 . One or more computer-readable storage media storing computer-readable instructions that, when executed, instruct one or more processors to perform operations comprising:
 receiving first and second images that at least partly represent a textured target;   producing multiple layers for each of the first and second images, the multiple layers representing the respective image at different resolutions; and   identifying a feature in a layer of the multiple layers of the second image from a relation of features in the multiple layers of the first image to determine a pose of the textured target.   
     
     
         22 . The one or more computer-readable storage media of  claim 21 , wherein the operations further comprise:
 utilizing the pose of the textured target to display augmented reality content in relation to the textured target, the augmented reality content being displayed simultaneously with a substantially real-time image.   
     
     
         23 . The one or more computer-readable storage media of  claim 21 , wherein the layer of the multiple layers of the second image has a higher resolution than another layer of the multiple layers of the second image.